<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>
  <script>
    // promise 接收一个参数  参数是一个函数，函数有两个参数，一个resolve,一个是reject
    let a = new Promise((resolve,reject)=>{
      
      var xhr = new XMLHttpRequest()
      xhr.open('post', 'http://localhost:3000/list')
      xhr.send()
      xhr.onreadystatechange = function(){
        if (xhr.readyState == 4) {
          let data = JSON.parse(xhr.responseText).data
          resolve(data)
        }
      }
    })
    
    a.then((data)=>{
      data.forEach(item => {
        document.body.innerHTML += `<p>${item.name}</p>`
      });
    })
  </script>
</body>
</html>